Apple Inc.'s iPhone is leading a new wave of gadgets using touch-sensitive screens that react to taps, swishes or flicks of a finger. The improvements promise to be slicker and more intuitive than the rough stomp of finger presses and stylus-pointing required by many of today's devices.

Apple has already been showing off its finger ballet in video ads ahead of the smart phone's hotly anticipated launch on June 29.

Glide a finger across the screen to activate the device and main menu. Slide your digit up or down to scroll through contacts. Flick to flip through photos. Tap to zoom in on a Web site.

With Apple's marketing machinery, the iPhone is poised to become the poster child for the new breed of touch-screen technology, which relies on changes in electrical currents instead of pressure points.

But the iPhone will have its fair share of rivals.

Shipments of this advanced strain of touch screens are projected to jump from fewer than 200,000 units in 2006 to more than 21 million units by 2012, with the bulk of the components going to mobile phones, according to a forecast by iSuppli Corp., a market research company.

"This new user interface will be like a tsunami, hitting an entire spectrum of devices," predicted Francis Lee, the chief executive of Synaptics Inc., a maker of touch sensors.

Synaptics' latest technology is in a growing number of cell phones, including LG Electronics Co.'s LG Prada touch-screen phone that launched this year in Europe and South Korea and handles gesture-recognition similarly to the iPhone.

Apple does not comment about its component suppliers, and Lee declined to comment whether Synaptics is working with Apple on the iPhone.

Last fall, Nokia Corp.'s research and development unit unveiled online images of a prototype all-touch-screen cell phone called the Aeon, but the company hasn't disclosed any details of its features or market availability.

"Touch screens are going to be more common, period, because rivals will slap them on to compete with Apple," said Michael Gartenberg, an analyst at JupiterResearch.

Even before the iPhone hype kicked into high gear over the past few months, touch screens in general were becoming more popular in cell phones. About 38 million handsets, or about 4 percent of all mobile phones shipped in 2006, had touch-screen features — a figure that will grow to 90 million units by 2012, iSuppli projected.

But most touch-screen phones that shipped last year, including Palm Inc.'s Treo and Motorola Inc.'s ROKR E6, used "resistive touch" technology — the most common technology, said Jennifer Colegrove, a senior analyst of display technologies at iSuppli. It has two layers of glass or plastic and calculates the location of touch when pressure is applied with either a stylus or a finger.

A more advanced type of touch screen, featured on the iPhone and LG Prada, uses "projected capacitive" technology. A mesh of metal wires between two layers of glass registers a touch when the electrical field is broken.

Cell phone maker Pantech Co. Ltd., for instance, has a flip-phone in which Synaptics' capacitive sensors are below the keypad so users can do finger gestures atop the buttons to navigate the phone. The touch-sensitive navigation controls on the LG Chocolate cell phone also use capacitive technology.

The feather-like gestures that are possible with capacitive touch screens could feel more intuitive than the pokes needed on resistive touch screens that typically require a stylus or a fingernail to navigate. Capacitive touch screens are also generally brighter because their surface isn't covered with a thin film that's needed on resistive displays, Colegrove said.

However, users of capacitive touch screens will have to learn to adapt to new methods of input, which could vary depending on how the gadget's software is designed.

With High Tech Computer Corp.'s new HTC Touch smart phone, users swipe a finger to scroll. A second swipe speeds up the scrolling.

"We've been doing touch screens for a long time, but this generation of touch screens is definitely breathing new life into the experience," said Todd Achilles, vice president of HTC American. "They're more accurate, more responsive, and you can get what you want to do on the first click."

Immersion Corp., a maker of tactile-feedback technology found in game controllers and other devices, added a vibration feature to go with the LG Prada touch screen and expects 10 more cell phones with advanced touch-screen technology to be introduced by other handset makers later this year.

The feature gives a slight vibration sensation when the touch screen's virtual keyboard is tapped. It's similar to the response users are accustomed to getting from mechanical keyboards.

But the iPhone is the only cell phone that can handle more than one finger at once, analysts say. That technology, which Apple has patented, allows users to resize a window, for instance, by pinching or expanding two fingers on the display.

"Multi-touch" technology is not new but has only recently begun to emerge beyond research labs and product prototypes.

New York University research scientist Jeff Han has developed a large, dazzling multi-touch touch-screen computer display where one could manipulate pictures or data with multiple fingers, and founded Perceptive Pixel last year to market the technology.

Meanwhile, Microsoft Corp. has introduced a coffee-table shaped computer and display that responds to multiple touches at once. The commercial machines are set to begin appearing in some hotels later this year.

But, Colegrove said, the iPhone will be the first product that puts the multi-touch feature in a mainstream consumer's hands — at a retail price of $500 to $600.

With Synaptics' Onyx concept phone unveiled last fall, the component maker claims its capacitive technology can do everything that Apple has shown the iPhone's touch screen can do. But no cell phone makers, other than Apple, appear to have developed the software applications to take advantage of multi-touch features yet, Lee said.

Industry observers say it's only a matter of time before that changes.

"The iPhone," Colegrove said, "is going to be a catalyst for this technology."

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